Product data

AccuRater
It is extremely important that all refrigerant lines and the AccuRater metering device be insulated on heat pumps. On
cooling only units, the liquid line may be left un-insulated. Use any acceptable heat resistant closed-cell foam insulation
(minimum 3/8-in. wall thickness). When insulating piping, cap ends and slide insulation over the piping. Insulation can
also be cut and placed over piping.
For the outdoor unit only, install flare connection on tubing to liquid line at fan coil unit. A piston is shipped in the
AccuRater device body (Fig. 13) with the indoor unit. See Piston & Charge Combination Section #14 to verify that you
have the required piston size for the system being installed.
IMPORTANT: The factory-supplied piston MUST be in-stalled as shown in Fig. 13.
NOTE: DO NOT install a piston on Multi Split systems. Refrigerant control is handled by a TXV (thermostatic expansion
valve) in the outdoor unit in these systems.
For special applications, such as long lines or raised elevations, consult the Refrigerant Lines & Long Line Application
Section #15 for specific system requirements.
IMPORTANT: The arrow on the AccuRater device body must face away from the indoor coil.
On heat pump installations, install factory-supplied piston (enclosed in a bag taped inside the outdoor unit) into the
AccuRater-metering device located in the service valve on the outdoor unit (Fig. 14).
IMPORTANT: The factory-supplied piston MUST be in-stalled as shown in Fig. 14.
Make sure Teflon seal on the piston faces toward the outdoor unit. See Piston & Charge Combination Section #14 to verify
you have the required piston size for the system being installed. For special applications, such as long lines or raised
elevations, consult Refrigerant Lines & Long Line Application Section #15 for specific system requirements.
Refer to Installation, Start-Up and Service Instructions for additional outdoor unit installation information.
Install a liquid line filter drier near the outdoor unit. On heat pump systems, a biflow filter drier must be used.
Cleaning and/or Replacing
The piston has a refrigerant metering hole through it. The retainer forms a stop for the piston in the refrigerant bypass
mode and a sealing surface for the liquid line flare connection. To check, clean or replace the piston:
1. Shut off power to unit
2. Pump down using proper Pump Down procedures
3. Remove liquid line flare connection from AccuRater device
4. Pull retainer out of body being careful not to scratch flair sealing surface. If retainer does not pull out easily, carefully
use locking pliers to remove retainer
5. Slide piston out by inserting a small soft wire, with small kinks, through the metering hole. Ensure metering hole,
sealing surface around piston cones, and fluted portion of piston are not damaged
6. Clean piston refrigerant metering hole
7. Replace retainer O-Ring before reassembling AccuRater device. (O-Ring part No 99CC501052)